54 
This description, or rather these distinctions, of Mr. Chambers apply 
to some examples, while to others they do not. Many specimens are 
very roseate and richly colored, while a few appear almost plain black 
and dull white. The three species are best distinguished in the larva 
state, in which there are very decided differences. G. roseosuffusella 
feeds on Clover, G. rubensella on Oak, while the species under con- 
sideration, so far as my observations show, is confined to Apple. The 
larval characters are also very diverse in the three species. 
EXPERIMENTS WITH INSECTICIDES. 
During the great prevalence of Aphididae in the spring I made much 
use of pyrethrum and of the X. O. dust. Of the value of the former as 
a remedy for these pests, except in the case of one or two species, I 
have no occasion to change the favorable opinions already repeatedly 
published. The X. O. dust was thoroughly tested on the following 
Aphids: Aphis mali and Schizoneura lanigera on Apple; Aphis prunifolit 
on Plum; Siphonophora rose on Rose; Myzus persice on Peach; Aphis 
brassice on Cabbage; Aphis sp.? on Cucumbers and Squash; Siphono- 
phora sp.? on Lettuce; S. crategi on Thorns; S. rudbeckie on Solidago; 
Aphis ambrosic ou Ambrosia trifida, and Aphis chrysanthemi? on Chrys- 
anthemum. With its effects on all of these I was well satisfied, although 
in some cases it took several dustings to thoroughly clear a plant. 
When applied with a powder bellows it causes the insects to drop to the 
ground at once, where they may be pressed into the soil with the foot or 
patted down with a trowel. The more delicate species succumb to a 
single thorough dusting and never recover from the effects of contact 
with the powder. This preparation will also destroy Siphonophora 
avence, but whether it could in any way be applied to a field of infested 
grain has not been demonstrated. 
The Black Chrysanthemum Aphis is one of the greatest pests of the 
flower garden and gives much trouble to both amateurs and profes- 
sional florists. It hibernates on the plant and attacks the stolons as 
soon as they appear in the spring, and unless great care is taken to 
eradicate it, it is more or less numerous on the plants throughout the 
summer, dwarfing and deforming them by its punctures and by the loss 
of sap which it appropriates. As soon as the buds are formed it seems 
to develop with four-fold fecundity and requires assiduous attention to 
keep in check. The Buhach or pyrethrum powder is utterly useless 
against this species, probably because the plant from which it is made 
is so close an ally of the Chrysanthemum. The X. O. dust, composed 
of creosote and tobacco, is the best remedy within my knowledge, killing 
the Aphis without the slightest injury to the plant. Ihave found it 
best to apply during the middle of the day when the dew is off. A few 
minutes after dusting the plants, I pass along the rows or among the 
pots, and give each branch a smart shake or a blast of air from the 
empty puff, and every Aphis that has not previously dropped is dis- 
